Gear lapping machine



Oct. 12, 1954 F. E. M MULLEN ETAL 2,691,250

GEAR LAPPING MACHINE Original Filed Aug. 24. 1951 4 Sheets-Sheet 1 INVENTORS FREDERICK E. McMULLEN BY THEODORE H. PECK ATTORNEY FIG.

Oct. 12, 1954 F. E. MCMULLEN ETAL 2,691,250

GEAR LAPPING MACHINE Original Filed Aug. 24, 1951 4 Sheets-Sheet 2 1 j I26 I21 I25 1 I z 9 j 2 1 2 H8 3 g I22 7 l2! -|29 INVENTORS I23 FREDERICK E. MCMULLEN I THEODORE H. PECK 4 FIG?) FIG. 4 ATTORNEY Oct. 12, 1954 MCMULLEN ETAL 2,691,250

GEAR LAPPING MACHINE 4 Sheets-Sheet 3 Original Filed Aug. 24, 1951 INVENTORS FREDERICK E .McMULLEN BY THEODORE H. PECK 4 441. 7

A TTQRNEY Oct. 12, 1954 McMULLEN ETAL 2,691,250

GEAR LAPPING MACHINE Original Filed Aug. 24, 1951 4 Sheets-Sheet 4 .IO IO mmvrolzs FREDERICK E. McMULLEN THEODORE H. PECK ATTORNEY Patented Oct. 12, 1954 4 UNITED STATES PATENT OFFICE GEAR LAPPING NIACHINE Frederick E. Mclilullen, Rochester, and Theodore H. Peck, Irondequoit, N. Y., assignors to The Gleason Works, Rochester, N. Y., a corporation of New York Original application August 24, 1951, Serial No. 243,402, new Patent No. 2,639,557, dated May 26, 1953. Divided and this application August 16, 1952, Serial No. 304,742

13 Claims. (oi. 5l-26) l The present invention relates to an improved cally operate the piston to door-opening position machine for lapping gears, and is a division of after the main drive motor has stopped at the our application Serial No. 243,402, filed August conclusion of the lapping operation.

24, 1951, now Patent No. 2,639,557, granted May This stopping preferably is effected automati- 26, 1953. cally by sequence control means which acts first The invention comprises improvements in the to stop the supply of lapping compound to the system for containing and circulating lapping gears, then after a-predetermined time lag to discompound, including means for preventing escontinue drive of the gears, and then, after ancape of the compound from the chamber of the other predetermined time lag, to open the doors. machine in which the gears are lapped. For m The first time lag preferably is of such duration the latter purpose a vertically sliding door for as to allow compound on the gears to be thrown the chamber is provided, the door carrying a from them by centrifugal action before their ronozzle for directing compound onto the gears tation is stopped, andthe second lag is prefwhen the door is closed. The compound, in liqerably suflicient to allow the gears to come to a uid suspension, drains into a sump beneath the 15 standstill by the time they become accessible to chamber, and is pumped from the sump to the the operator as a result of opening of the doors. nozzle through a flexible conduit. The consist- The foregoing and other objects and advanency of the compound is kept uniform by means tages of the invention will appear from the folof an agitator in the sump, but when the machine lowing description of the machine shown in the is not running the solid matter gradually settles. an accompanying drawings, wherein:

It has been found that if such solid matter is l is a plan view of the whole machine; allowed to gat in the pu p nlet, it may clog Fig. 2 is a side elevation of the machine viewed the pump and prevent it from starting. In order from the direction indicated by 2--2 in Fig. 1, to obviate this condition, while at the same time with parts broken away to show the sump for retaining the advantage of connecting the pump lapping compound and the traps in the passage inlet to the sump at a level close to the bottom between the sump and the inlet of the lapping of the sump, the pump inlet passage is arranged compound circulating pump;

to comprise a p Which Prevents ingress of the Figs. 3 and 4 are detail vertical sectional views s t d m t i to t p mp t ri x p taken respectively along lines c-3 and 4- 1 of When the p p is Operating Figs. 1 and 3, respectively, and show the door In addition to the verticallymovable door 215 a tuating means;

there is an uxili ry r vi y l d door hi Fig. 5 is a detail sectional view taken along on a horizontal axis and serving when closed as l 5 5 of i 4 t h th li it switch opthe top wall of the chamber. A single hydraulierated by the o r actuating means;

Cally operated pi n i ran d to ff D- Fig. 61s a diagram indicating one Way in which eration of both doors, being connected by a piv- ::i; t electrical ystem of the machine may be oted link to the auxiliary door, and to the vertiired; and,

cally movable door by means comprising two Fig. '7 is a diagram of that part of the maracks and intermediate pinions. One rack is hydraulic control system with which the carried by the piston, the other by the door, and invention is concerned.

the pinions are so proportioned that the stroke 2 As shown in Fig, 1 the machine includes a bed of the piston is substantially shorter than the :3; upgn hi h i e head 24 is mounted for travel of the d or- Th piv n which 0011- movement in the horizontal direction indicated nects the piston to the auxiliary door comprises by arrow g3 h pinion d gear t be lapped two parts having a play connection so that lowerare designated P and G, respectively, the pinion ing of the piston does not necessarily close the 3: being chucked upon a spindle journaled for roauxili ry d r, this arrangement b i empl yed tation in the head 24. The head may be adaS a Sa y meaSuIejusted upon the bed 2! in the direction of arrow A means is al o p v d 0 prevent Operation 23, by means including handwheel 22; such adof the main drive motor of the machine, which justment being employed t move t pinion rotates the gears being lapped, unless and until 55 horizontally, transversely of its axis, into the dethe doors are closed- For this Purpose a limit sired position of mesh with the gear G. Suit: switch in the control circuit of the Operating able means controlled by-a lever 25 serves to move motor is arranged to pr n motor Operation the head upon the bed, also in the direction of whenever the piston is away from its door-closed arrow .23, to withdraw the head from such adlimit position. Means are provided to automati justed position for the purpose of chucking and de-chucking the pinion and gear, and to advance the head toward such adjusted position. Final advance of the. head, to mesh the pinion with the gear, is efiected by manual operation of a jogger valve 26. Backlash of the desired amount between gear P and G may be obtained by manual operation of lever 25 conjointly with operation of levers 21 which control mechanism that retracts the pinion relative to head 24 (also in the direction of arrow 23) by a given amount after the head has been advanced to bring the gears into metal-to-metal mesh.

A column 28 is adjustable horizontally on bed 2! in the direction of arrow 29 by means which include handwheel 30. The spindle upon which the gear G is chucked is journalled in a head 3i which is movable vertically upon the column. Head 3! is adjustable vertically relative to the column 28 to vary the offset between the axes of the gears P and G, while by the means including handwheels 22 and 30 the gears may be adjusted along their respective axes to whatever mean position of mesh is desired. After the gears have been brought to such position they may be rotated first in one direction and then in the other by a suitable reversible main drive motor that is connected to the pinion spindle, and load may be applied to the gears by suitable braking means 32 or by a generator 40 connected with the gear spindle. While the gears are rotating the head 3! is oscillated through a small amplitude vertically, and simultaneously the gear spindle is oscillated laterally (in the direction of arrow 29) and also axially (the direction of arrow 23) through small amplitudes to effect the lapping over the entire working face of each gear tooth. Such oscillation is efiected by a reversible electric motor 53, Fig. 6, through mechanism which is fully described in our aforementioned application Serial No. 243,402. The lapping compound is directed upon the rotating gears from a nozzle designated 33.

During the lapping operation the gears P and G are enclosed in a chamber which has, as one side wall, a vertically disposed door I [2 on which the lapping compound nozzle 33 is mounted. The door is arranged to slide vertically on two guide rods H3 (only one of which is shown in Figs. 2, 3 and 4) secured to the machine bed 2! and to a member H4 that is mounted on the fixed wall structure H of the chamber. When lowered the door opens to provide access to the gears and. to carry the nozzle 33 to a position wherein it cannot direct lapping compound onto the gears. The upper wall of the chamber includes an auxiliary door H6 which is hinged to the fixed structure H5 on a horizontal axis, the hinge connection comprising hinge pins HT secured to the door. As shown the auxiliary door is horizontal when closed, and assumes a nearly upright position when opened to further provide access to the lapping chamber.

For operating the doors there is provided a hydraulically operated piston l 88 vertically mov able in a stationary cylinder H9. The lower end of the piston rod constitutes a rack i2! meshing with a pinion I22 that is mounted for rotation upon the fixed structure I i5. A larger pinion (23, rotatable as a unit with the pinion [22, meshes with a rack I2 3 provided on door H2. This arrangement is such that as the piston is raised and lowered between its limit positions, the door H2 is respectively lowered and raised through the much longer travel necessary to open and close it.

The upper end of the piston rod is pivoted at I25 to a connecting rod that in turn is pivoted at l2'i to a crank arm I28 keyed to one of the hinge pins Hi. As shown, the connecting rod 125 is made of two telescoping sections. Upon upward motion of the piston I 13, the crank arm 128 is rotated (clockwise in Fig. 3) as a unit with the auxiliary door H6, opening the latter. Upon downward motion of the piston, the auxiliary door is allowed to lower by gravity, but because of the play connection provided by the telescoping sections of rod lit the door is not positively closed by down motion of the piston. The play connection thus constitutes a safety means which may prevent possible serious injury to the machine operator should his arm or hand be in the path of the closing door. The play connection also enables the auxiliary door to be opened manually, at a time when the main door H2 is closed, to permit the operator to adjust the nozzle 35 to direct the fluid lapping compound onto the gears and G.

The door actuating mechanism controls the normally open two pole limit switch I29, shown in Fig. 5, which is arranged in the electrical control system of the machine. The stem of the switch is moved inwardly, to close the switch, by and upon counterclockwise motion of a pivoted lever Edi. The upper end of the lever is engaged and moved counterclockwise by a finger its as the latter moves clockwise. The finger is mounted to rotate as a unit with the pinions 22 and 23, and is arranged to close the switch i251 as the doors H2 and H6 reach their closed positions. Light springs 33 serve to hold the lever iSi in its neutral (switch open) position when it is not engaged by finger 132.

Beneath the lapping chamber is a sump for containing the lapping compound, which ordinarily consists of finely divided abrasive material in liquid suspension. To maintain the material well distributed in the liquid during machine operation, there is mounted in the sump an agitator comprising paddle wheels i235 mounted upon a rotatable shaft 35. This shaft is rotated by the main drive motor through suitable drive means within a drive housing \(l'l.

The lapping compound is drawn from the bot tom of the sump into the inlet of a pump Hi3 driven by a motor iSQ. From the pump outlet the compound is forced through tubing it! and M2 and nozzle 33 onto the gears P and G. The section M2 of the tubing is flexible to accommodate the opening and closing of the door M2 on which the nozzle 33 is mounted. The nozzle itself is preferably made up of articulated sections in order that the operator may easily it to direct the lapping compound on gears P and G of any size that may be placed on the machine. A trap Hi2, arranged in passage hill be tween the sump and the pump inlet, serves to prevent entrance into the pump of abrasive material that may settle out of the lapping compound while the pump motor and the main drive motor of the machine are not operating, as for example while the machine is standing idle over night.

Suitable seals are provided to prevent the lapping compound from entering the working parts of the machine. For example, bellowslike rubber seals Hi l are provided to protect the ways on which the heads 24 and 28 are adjustable, and rubber diaphragms M5 to prevent the compound from passing out of the lapping chamher around the spindles that support the gears P and G.

The machine contains a set over mechanism, fully described in our aforementioned application, for positioning the gears P and G in a different relationship while lapping one side of their teeth than while lapping the other side thereof. The set over mechanism operates in three directions, each at right angles to the other, one direction being vertical and the other two horizontal in the'direction of the axes of the two gears. The hydraulic control system for the set over mechanism is shown in the hydraulic diagram, Fig. 7. The system includes a sump I 5| for hydraulic fluid, a pump I52 operated by a motor I53 for applying the fluid under pressure to a vertical set over cylinder I04 operating in the direction of the axis of pinion P, a transverse horizontal set over cylinder 66 and an axial horizontal set over cylinder 85 operating in the direction of the axis of gear G. This application of pressure to the set over cylinders is controlled by an automatically operated solenoid actuated reversing valve I54 and manually set reversing valves I55 and I56. Pressure is also applied from the pump I52 to the door actuating cylinder H9 (Figs. 3 and 4), being controlled automatically by a solenoid actuated reversing valve I57.

The condition shown in the Fig. 7 is that solenoid I55 has been energized while solenoid I58 has been deenergized (the solenoids being of the repulsion type), so that the valve I 54 has been moved to its left limit position and thereby connects pressure line IEJI with line I62 and connecting exhaust line IE3 (which returns to the sump) with line I64. Lines I52 and I6 communicate respectively with the right and left ends of cylinder 65, so that the latter is retained in its right limit position relative to its stationary piston 6?. Valve I55 has been manually moved to the left, and so connects line I52 with a line I65 communicating with the right end of cylinder 85; and also connects line I 64 with a line I66 leading to the left end of cylinder 85. Thereiore piston 84 is held in its left limit position. Valve I56 has also been manually moved to the left, thus connecting line I62 with a line I57 to the bottom of cylinder IE4, thus holding the piston I53 in its upper limit position.

When the solenoid I59 is de-energized and solenoid I58 is energized, thereby moving valve I54 to its right limit position; the line I52 is connected, via valve passage I69 with return line I83, and line IE4 is connected with pressure line IISI. As a result the cylinder 63 will be set over to the left, piston 84 will be set over to the right, and piston I 53 will be set over downwardly by the weight of the parts it supports.

By manually shifting valve I55 to its right limit position the connections of lines I52 and I 64 with lines I I35 and Itt are reversed, I52 being brought into communication with I I36, and I6 3 connecting with IE5 through valve passage I7I. As a result the direction of set over of piston .84 will be reversed relative'to that of the cylinder ta Similarly by manually shifting the valve I56 to its right limit position the .line IE7 is connected through valve passage I72 with line I64, so that the position of set over of piston 13 is reversed with respect to that of cylinder 66.

The valve I57 is brought to the position shown in Fig. 7 by energization of solenoid I74 and de-energization of solenoid I73. In this position pressure line I6I is connected with a line I75 that extends to the lower end of door actuator cylinder II 9, and return line I63 is connected with a line I76 to the upper end of the cylinder. Thus the piston is held in its uppermost position in which the lapping chamber doors II2 and H5 are open. When the valve I57 is shifted to its right position by ene'rgization of solenoid I73 and de-energization of solenoid I74, the pressure and return line connections to the cylinder are reversed and the doors are closed. In this latter condition the limit switch I29 is closed as has been explained hereinbefore.

The elements of the electrical control system of the machine are contained largely in a cabinet designated I III in Fig. 1. The system may be basically like that disclosed in the L. E. Turner et al. Patent No. 2,445,649 granted July 20, 1948, and to avoid needless repetition of description therein contained, Fig. 6 shows in light lines the identical wiring diagram shown in Fig. 18 of said patent. Connections omitted in the present machine from what is shown in the patent are indicated in Fig. 6 by light dash-dot lines, while the connections and apparatus new in the present machine are shown by heavy lines.

As shown in Fig. 6 the solenoids I58 and I59 are connected, between main leads L1 and L2 of a three wire source of electricity, in parallel with the reverse and forward windings I82 and I83 of a controller I84 for the main drive motor I85 of the machine, the connections including a manually operated reversing switch I 86. With the position of the switch that is shown, the solenoid I58 is energized simultaneously with coil I82, and solenoid I59 with I 83, but by reversal of switch IBIS during the set up of the machine, solenoid I58 will be energized simultaneously with coil I83, and solenoid I 59 simultaneously with coil I82. This enables reversal of the direction of the transverse horizontal set over (by cylinder 66) relative to the direction of rotation of the main drive motor.

The lapping compound pumping motor I39 has a controller I87 which when energized connects the motor to the main leads L1, L2, and L3. The .coil of the controller is connected in series with start switch button I 88 in a circuit between leads L1 and L2, so that as soon as the start button is pressed the motor I39 will start. The holding relay I89, which when energized establishes a shunt circuit around the start button, remains energized during the lapping cycle of the machine, and is de-energized at the conclusion of the cycle as a result of the switch arm I9I closing against the contact at station No. 9 of ratchet relay I92.

The door controlling solenoids I73 and I74 are subject to control by relays I83, I94, and I; and the main motor I85 and the oscillating motor 53 are subject to control by relay I93 and I95 and limit switch I 29. The coil of relay I93 is connected in parallel with the coil of holding relay Hi9 and hence remains energized throughout the lapping cycle. Relay I94 is a time relay primarily for controlling the door, and i of a type which when energized opens its contact immediately, and when de-energized closes the contact after a predetermined time lag. The relay I95 is also of this general type, and when energized immediately closes its contact I St and opens its contact I97. When ole-energized it closes I9! and opens I 36 after a predetermined time delay.

As shown the solenoid I74 is connected across leads L1 and L2 in series with contacts of relays I94 in such manner that it is energized when relay W3 is de-energized and the contact of relay 1% is closed (when relay Hi l has been de-energized for a time). Solenoid H3 is connected across leads L1 and L2 in series with accntact of relay 183 so as to be energized whenever the latter is energized. The coil of relay {9 3 is connected across leads L1 and L2 in series with contact ifit or the spin time relay m5, and hence is energized when the latter is.

The upper movable contact or limit switch I29 is connected between leads L1 and L2 in series with contact 536 of relay 5% and, through a switch arm of relay Hill, with a winding of motor controller Ell-3 which are reversed by relay 5539. The lower movable contact of limit switch E29 is connected between leads in and L2 in series with a switch arm of reversing relay E99 and a winding of controller Edi for oscillating motor 53. Controller 24H has forward and reverse windings 2G3 and 2851 which are alternately energized by the relay 189 under the control of the reversing switch mechanism 62. It will be noted that the branch circuits including contact Ito and limit switch 525 replace connections (here designated 282) of the prior art circuit.

Before a lapping operation is commenced, the gears P and G are mounted and the machine is adjusted to bring them to the desired mean position of mesh for lapping one side of their teeth; and the switch :88 and valves I55 and B- are set. Then the start button 83 is pressed momentarily resulting in the following sequence:

(1) A circuit between lines L1 and L2 is established through switch arm i531 of ratchet relay Hi2 and the right winding of relay 2B5, closing the right contact of the latter and thereby establishing a circuit which energizes relays H39 and 193. The closing of the left contact of relay 15S establishes a shunt around start button 883 so that release of the latter does not affect operation of the machine. Th energization of relay 293 causes solenoid B3 to be energized, thereby shifting valve 15'! to the right, causing piston iii to move down, closing the lapping chamber doors.

(2) Simultaneously with (1) controller i3! is energized startin the lapping compound pump motor its.

(3) Also simultaneously with (1) the spin time delay relay 395i is energized, immediately closing its contact we and opening its contact iiil. Closing of 96 energizes door time delay relay ltd, immediately opening the latters contact in the circuit of solenoid lid (this circuit also being opened at this time by relay i533) l) As the lapping chamber doors become fully closed, the limit switch i'iii (Figs. 4, 5 and 6) is closed. This establishes a circuit from L1 to L2 through the now closed contact E95 of the spin time delay relay the upper contact of limit switch 529, and winding 53?. of main drive motor controller it (through a contact of relay l ll). The main drive motor i 35 is thus put into operation. The closing of switch 12?: also closes a circuit from L1 to L3 through the right contact of relay i553 and the left winding of motor controller thereby putting the oscillating motor 53 into operation.

(5) Simultaneously with (4) i. c. with energization of winding 532, the solenoid IE3 is energized, with the result that the set over control valve ifi l is moved to the right (Fig. 7) causing set over by lowering of piston Hi3, and movement to the left of piston Se and cylinder 56.

(6) The lapping operation now proceeds with functioning of the control systems as described in detail in the prior art, the oscillation motor reversing after turning the cam 43 through the desired angle in each direction.

(7) After lapping of one side of the gear teeth has been completed the relay I89 reverses, deenergizing winding I82 and energizing winding E33 of the motor controller in. This causes the motor N25 to reverse so that the drive through gears P and G is on the other side of their teeth.

(8) Simultaneously with (7) solenoid I58 is ole-energized and solenoid 159 is energized, shifting the set over valve [5% to the left and thereby effecting movement of pistons I93 and 84, and of cylinder 5t, to the respective positions shown in Fig. '7.

(9) The lapping of the other side of the teeth now proceeds, with the oscillating motor 53 reversing after turning the cam through the desired angle in each direction.

(10) As the foregoing operations take place the switch arm Hill of the ratchet relay 192 is advanced and at the conclusion of lapping is advanced to close the contact at station No. 9. This energizes the left coil of relay 2&5, thereby tie-energizing relays I39, 93, and 195.

(11) The de-energization of the holding relay Hi9 results immediatel in opening of the circuit through the coil of controllers 1187, so that the lapping compound pump motor is stopped. The de-energization of relay 153 results in door control solenoid H3 being de-energized immediately, but this is without immediate efiect since the other door control solenoid l'f l is not immediately energized. De-energization of 489 also stops oscillating motor 56.

(1 With a delay after (11) preferably long enough to allow excess lapping compound to be spun off the gears P and G, the contact 196 of relay i555 opens and contact 19'! closes. Closing of is? establishes a circuit from L1 to L2 through the now closed, right contact of relay I89, left contact of relay 295 and right coil of reversing relay lei-i, to thereby condition the coil 43?: of motor controller for energization on the next lapping cycle. Opening of I95 lie-energizes relay I94 but this has no immediate effect.

(13) Simultaneously with (12) the opening of contact I96 of relay breaks the circuit (through limit switch I29) for the winding of motor controller 184, so that the main drive motor I85 is de-energized.

(14) With a delay after (13), preferably long enough to allow the gears P and G to coast to a stop, the contact of relay I94 closes, thereby establishing the circuit through solenoid H 1. Valve I5! is thereupon shifted to the left, causing the piston H8 to be elevated and thereby opening the lapping chamber doors so that the now finished gears P and G may be removed.

The foregoing disclosure of the machine and its mode of operation is made by way of example to illustrate and explain the inventive principles involved, and not by way of limitation, for as those skilled in the art will recognize, various changes and modifications may be made readily without departing from the spirit of the invention or from the scope of the appended claims.

We claim as our invention:

1. A gear lapping machine having a chamber into which project a pair of spindles for gears to be run in mesh in the chamber, power means for rotating one spindle to effect rotation of the other spindle through the meshing engagement of the gears, a vertically disposed door arranged for vertical movement between open and closed positions, said door when raised closing one side of the chamber, another door hinged at one side on a substantially horizontal axis and so arranged that when lowered it closes the top of the chamber, said other door being arranged to close by gravity, a vertically movable piston having a rack movable therewith, a rack on the vertically disposed door, gearing operatively connecting said racks and so proportioned and arranged that the vertically disposed door moves oppositely to and has a longer travel than the piston, and a lost motion connection between the piston and said other door for raising the latter upon upward movement of the piston and permitting the piston to lower without said other door necessarily lowering.

2. A gear lapping machine having a chamber into which project a pair of spindles for gears to be run in mesh in the chamber, a vertically disposed door arranged for vertical movement between open and closed positions, said door when raised closing one side of the chamber, an other door hinged at one side on a substantially horizontal axis and so arranged as to lower to closed position by gravity, and power means to open and close said doors having a lost motion connection with said other door which permits operation of the power means in a direction to close said doors without said other door necessarily being lowered.

3. A machine according to claim 2 in which there is means for directing lapping compound onto the gears, the last mentioned means including an adjustable nozzle mounted on the vertically disposed door for vertical movement therewith.

4. A machine according to claim 2 in which said power means comprises a vertically movable piston having a rack movable therewith, a rack on the vertically movable door, and gearing operatively connecting said racks, and in which said lost-motion connection is between the piston and said other door.

5. A machine according to claim 2 in which said power means includes a vertically movable piston and said lost motion connection comprises a rod pivotally connected to the piston and to said other door for raising the door upon movement of the piston in one direction, and said rod having telescoping sections permitting movement of the piston in the opposite direction with. out necessarily lowering said other door.

6. A gear lapping machine having a chamber for gears that are to be run in mesh, a sump at a level below said chamber for containing a lapping compound in liquid suspension, means for directing the compound against the gears including a pump disposed at a level near to that of the bottom of the sump, and a passage leading from the sump at a level near said bottom into the pump inlet, said passage comprising a trap to exclude from the pump lapping compound which may settle from suspension in the sump while the pump is not operating.

7. A gear lapping machine having a chamber containing means rotatably supporting the gears to be lapped, a door for the chamber and a door actuator, drive means for rotating the gears, fluid supply means for directing a fluid lapping compound against the rotating gears, means for discontinuing operation of the fluid supply means, time delay means for discontinuing operation of said drive means with a predetermined time lag after operation of the fluid supply means is discontinued, and time delay means for operating the door actuator to open the door with a predetermined time lag after operation of said drive means is discontinued.

8. A gear lapping machine having a chamber containing means rotatably supporting the gears to be lapped, a door for the chamber and a door actuator, a first motor for rotating the gears, pump means operated by a second motor for directing lapping compound against the rotating gears, means for de-energizing the second motor, means for de-energizing the first motor with a predetermined time delay after the second motor is de-energized, and means for operating the door actuator to open the door with a predetermined time lag after the first motor is de-energized.

9. A gear lapping machine having a chamber containing means rotatably supporting the gears to be lapped, a door for the chamber and a door actuator, fluid supply means for directing a fluid lapping compound against the rotating gears, means for discontinuing operation of the fluid supply means, and time delay means for operating the door actuator to open the door with a predetermined time lag after operation of the fluid supply means is discontinued.

10. A gear lapping machine having a chamber containing means rotatably supporting the gears to be lapped, a door for the chamber and a door actuator, pump means including a motor for directing lapping compound against the rotating gears, means for de-energizing the motor, and means for operating the door actuator to open the door with a predetermined time lag after the motor is de-energized.

11. A gear lapping machine having a chamber containing means rotatably supporting the gears to be lapped, a door for the chamber and a door actuator, drive means for rotating the gears, fluid supply means for delivering a fluid lapping compound to the gears, means for discontinuing such delivery, time delay means for discontinuing operation of said drive means with a predetermined time lag after delivery of the lapping compound is discontinued, and means for operating said actuator to open the door with a predetermined time lag after operation of the drive means is discontinued.

12. A gear lapping machine having a chamber containing means rotatably supporting the gears to be lapped, a door for the chamber and a door actuator, fluid supply means for delivering a fluid lapping compound to the gears, means for discontinuing such delivery, and means for operating said actuator to open the door with a predetermined time lag after delivery of the lapping compound is discontinued.

13. A gear lapping machine having a chamber containing means rotatably supporting the gears to be lapped, a door for the chamber and a door actuator, drive means for rotating the gears, means for discontinuing operation of the drive means, and means for operating said actuator to open the door with a predetermined time lag after operation of the drive means is discontinued.

References Cited in the flle of this patent UNITED STATES PATENTS Number Name Date 1,095,593 Pike et a1. May 5, 1914 1,734,002 Belden Oct. 29, 1929 1,873,152 Plantinga Aug. 23, 1932 1,996,842 Stevens Apr. 9, 1935 2,111,170 Condon Mar. 15, 1938 

